Ecofriendly synergists for insecticide formulations (EcoSyn): in vitro and in vivo evaluation of novel synergists against Musca domestica

In the framework of the EU-funded EcoSyn project, laboratory bioassays and biochemical analysis were performed to evaluate the performance against Musca domestica L. (Diptera, Muscidae) of novel potential synergists in combination with a pyrethroid and a growth regulator (IGR) insecticide. The well known synergist piperonyl-butoxide (PBO) was included in the list to be used as a standard reference. Bioassays has been carried out against two resistant populations evaluating the effects against adults (pyrethroid) or larvae (IGR). Synergist significantly improved the efficacy of insecticides in bioassay against housefly. A few biochemical tests were performed to measure total activity of oxidases and GSTs in the same populations and to comparison with those of a full susceptible strain (S-WHO). These enzymatic activities were always higher than those of the susceptible reference strain. It was also investigated the “in vitro” inhibitory efficacy of PBO and that of new hypothetical synergists. In almost every case the novel synergists gave various levels of oxidases inhibition and in some cases performed better than PBO. Among the potential synergist assayed just one did not inhibited oxidases. But this was the only product giving a visible level of inhibition of GST activity.